Sheet finishing apparatus

ABSTRACT

According to an aspect of the invention, a shifter shifts sheets before stapling in a continuous stapling mode. A bundle of sheets is immediately discharged from the shifter after the stapling. In a sorting mode, the bundle of sheets is discharged from the shifter while the bundle of sheets is shifted in a direction perpendicular to a discharge direction of the bundle of sheets. A friction force applied to a bundle of sheet T in the discharging is distributed in the discharge direction and a direction perpendicular to the discharge direction.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from provisional U.S. Applications 61/016,933 filed on Dec. 27, 2007 and 61/024,530 filed on Jan. 29, 2008, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a sheet finishing apparatus capable of finishing sheets on which an image is formed by an image forming apparatus of a copier, a printer, or a multi-functional peripheral.

BACKGROUND

A sheet finishing apparatus capable of sorting sheets supplied from an image forming apparatus to staple the sheets is known.

As the sheet finishing apparatus, an apparatus which shifts sheets for preventing a plurality of needles from overlapping in a stapling mode to discharge the sheets after stapling of the sheets is disclosed in JP-A-2-23150, for example. Moreover, JP-A-2-23150 discloses the apparatus capable of shifting every group of sheets in a placing table and discharging a bundle of sheets in a sorting mode.

However, in the known apparatus, discharging the bundle of sheets is started late, since the bundle of sheets is discharged after stapling of the sheets or shifting of the group of sheets placed in the placing table. In order to shift the bundle of heavy plural sheets, a shift mechanism having large driving torque is necessary. In the sorting mode, a problem may occur in that sheets which are longitudinal in a discharge direction or are weak in resilience (no restoration property) are curved in the discharge direction when discharged and thus it is difficult to discharge the sheets.

Accordingly, it is preferable to devise a sheet finishing apparatus capable of improving an image forming performance and a sheet finishing performance by allowing discharging of sheets not to be started late in discharging of the bundle of sheets and suppressing an increase in the torque of a shift mechanism.

SUMMARY

According to an aspect of the invention, a performance for discharging a bundle of sheets is improved and alignment of the bundle of sheets in the discharging is improved.

According to the aspect of the invention, a sheet finishing apparatus includes: a processing tray which stacks a plurality of sheets supplied from a predetermined position; a processing member which finishes the sheets; a receiving member which receives the plurality of sheets discharged from the processing tray; and a sheet transporting member which transports the sheets from the processing tray to the receiving member while shifting the plurality of sheets in a direction perpendicular to a discharge direction of the sheets.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating the configuration of a finisher connected to a copier according to a first embodiment;

FIG. 2 is a schematic diagram illustrating the configuration of the finisher according to the first embodiment;

FIG. 3 is a schematic diagram explaining a waiting tray according to the first embodiment;

FIG. 4 is a schematic perspective view illustrating a processing tray when viewed from the waiting tray according to the first embodiment;

FIG. 5 is a schematic perspective view illustrating the processing tray and a transport mechanism when viewed from a stacking tray according to the first embodiment;

FIG. 6 is a schematic explanatory diagram illustrating a driving system of longitudinal alignment according to the first embodiment;

FIG. 7 is a schematic explanatory diagram illustrating a driving system of the transport mechanism according to the first embodiment;

FIG. 8 is a schematic explanatory diagram illustrating discharge of a bundle of sheets by ejectors and discharge rollers according to the first embodiment;

FIG. 9 is a schematic explanatory diagram illustrating discharge of the bundle of sheets by a binding claw and discharge rollers according to the first embodiment;

FIG. 10 is a schematic explanatory diagram illustrating a driving system of a transverse alignment plate according to the first embodiment;

FIG. 11 is a schematic perspective view illustrating a stapler according to the first embodiment;

FIG. 12 is a schematic explanatory diagram illustrating a driving system of the stapler according to the first embodiment;

FIG. 13 is a block diagram illustrating a control system of a finisher according to the first embodiment;

FIG. 14 is a schematic explanatory diagram illustrating operations in a continuous stapling mode according to the first embodiment;

FIG. 15 is a timing chart illustrating driving timing in the continuous stapling mode and driving timing according to a first comparative example according to the first embodiment;

FIG. 16 is a schematic explanatory diagram illustrating operations in a sorting mode according to the first embodiment;

FIG. 17 is a schematic explanatory diagram illustrating receiving of the bundle of sheets to the stacking tray in the sorting mode according to the first embodiment;

FIG. 18 is a schematic explanatory diagram illustrating the bundle of sheets aligned on the basis of a center reference according to a second embodiment; and

FIG. 19 is a schematic explanatory diagram illustrating the bundle of sheets aligned on the basis of a front reference according to the second embodiment.

DETAILED DESCRIPTION

Hereinafter, a first embodiment will be described in detail with reference the accompanying drawings. FIG. 1 is a schematic diagram illustrating the configuration of a copier 100 as an image forming apparatus and a finisher 7 as a sheet finishing apparatus which is connected to the copier 100 according to the first embodiment.

The copier 100 includes a placing table 112 of documents D in the upper surface. An automatic document feeder (ADF) 107 which feeds each of the documents D to the placing table 112 is disposed above the placing table 112. The documents D are loaded in the ADF 107 and image forming conditions (for example, an operation or non-operation of stapling, details of the stapling, a copy number of sheets, and the size of the sheets) are set. When copying is started, the ADF 107 allows the documents D to travel across a lead glass 112 a of the placing table 112 and then a scanner unit 104 reads an image of each of the documents D.

The copier 100 includes the scanner unit 104, a printer unit 106 which is an image forming member, and a sheet feeding unit 108. A charging unit 130, a development unit 146, a transfer removing charger 148, and a drum cleaner 131 are disposed in the vicinity of a photoconductive drum 144 of the printer unit 106. A laser exposure unit 141 radiates exposure light between the charging unit 130 and the development unit 146 in the vicinity of a photoconductive drum 144. The laser exposure unit 141 oscillates exposure light on the basis of information on the image of the document D read by the scanner unit 104. When the exposure light is radiated, an electrostatic latent image is formed on the photoconductive drum 144. The development unit 146 supplies toner to the photoconductive drum 144 in order to form a toner image by developing the electrostatic latent image formed on the photoconductive drum 144.

The sheet feeding unit 108 includes first to third sheet feeding cassettes 152, 153, and 154 which receive sheets P, a large-capacity sheet feeding mechanism 155, and a manual sheet feeding mechanism 156. The sheet feeding unit 108 feeds each of the sheets P to a location of the transfer removing charger 148 in synchronization with the toner image on the photoconductive drum 144. The transfer removing charger 148 transfers the toner image on the photoconductive drum 144 onto the sheets P and separates the sheets P from the photoconductive drum 144. The sheets P having the toner image are fixed by a fixing unit 160. After the fixing, the sheets P are transported to discharge rollers 161 or a re-transport unit 162. The sheets P are supplied from the discharge rollers 161 to the finisher 7. The sheets P are re-transported from the re-transport unit 162 to the location of the transfer removing charger 148.

As shown in FIG. 2, the finisher 7 includes entrance rollers 10 accepting the sheets P on which an image is formed by the copier 100 and which are discharged from the discharge rollers 161. The sheets P accepted by the entrance rollers 10 are discharged to a fixing tray 12 by first exit rollers 11. The sheets P accepted by the entrance rollers 10 are supplied to a processing mechanism 14 by second exit rollers 13. A gate flap 16 distributes the sheets P accepted by the entrance rollers 10 in a direction of the first exit rollers 11 or a direction of the second exit rollers 13.

The processing mechanism 14 includes a processing tray 17 which is a processing tray in which the plurality of sheets P supplied from the second exit rollers 13 are placed, a transverse alignment plate 18 which may be a processing member and a shifter shifting the sheets P placed in the processing tray 17, a stapler 20 which is a processing member and a staple member stapling the sheets P placed in the processing tray 17, a stacking tray 21 which is a receiving member receiving the sheets P discharged from the processing tray 17, and a transport mechanism 24 which is a sheet transporting member transporting a bundle of sheets as plural sheets on the processing tray 17 to the stacking tray 21.

A waiting tray 22 in which the sheets P supplied from the second exit rollers 13 temporarily wait is disposed above the processing tray 17. The waiting tray 22 waits for a previous bundle of sheets on the processing tray 17 to be finished. During finishing of the previous bundle of sheets, a subsequent bundle of sheets is able to be discharged to the waiting tray 22.

As shown in FIG. 3, the waiting tray 22 includes a front buffer tray 22 a and a rear buffer tray 22 b. When the previous bundle of sheets on the processing tray 17 is transported, the front buffer tray 22 a is slid to a front side and the rear buffer tray 22 b is slid to a rear side. The sheets P on the waiting tray 22 drop to the processing tray 17. The front buffer tray 22 a and the rear buffer tray 22 b are slid through a timing belt 23 a by a buffer tray guide motor 23.

As shown in FIGS. 4 and 5, the processing tray 17 includes a platform 17 a on which the sheets P dropping from the waiting tray 22 are placed and stacked. The platform 17 a has an inclination which is higher on a side of the stacking tray 21 in a transport direction of the sheets P. Rear end stoppers 17 b and longitudinal alignment rollers 17 c are provided on a rear end side in the transport direction of the sheets P on the platform 17 a. Discharge rollers 27 are provided on a front end side in the transport direction of the sheets P on the platform 17 a. As shown in FIG. 6, a paddle 26 is disposed above the rear end side in the transport direction of the sheets P on the platform 17 a. The paddle 26 is driven by a paddle motor 26 a.

As shown in FIGS. 5 to 7, the longitudinal alignment rollers 17 c are driven by a longitudinal alignment motor 28. A timing belt 28 a is suspended between a shaft 17 d of the longitudinal alignment rollers 17 c and a shaft 27 a of the discharge rollers 27. The discharge rollers 27 are driven through the timing belt 28 a by the longitudinal alignment motor 28. A bundle of sheets T stacked in the platform 17 a is regulated in a rear portion thereof in the transport direction by the rear end stoppers 17 b and is subjected to longitudinal alignment in succession by the longitudinal alignment rollers 17 c, the discharge rollers 27, and the paddle 26.

The transport mechanism 24 includes a pair of ejectors 24 a protruding from the rear end surface of the platform 17 a, a binding nail belt 30 between the pair of ejectors 24 a, and the discharge rollers 27. The ejectors 24 a push the bundle of sheets T from the platform 17 a. The binding claw belt 30 includes a binding claw 31. As shown in FIG. 7, the binding claw belt 30 is driven by a binding claw motor 32. An ejector clutch 33 is connected in order to deliver the driving of the binding claw motor 32 to the ejectors 24 a. The binding claw belt 30, the binding claw 31, and the discharge rollers 27 form a travel member.

As shown in FIG. 8, the bundle of sheets T on the platform 17 a starts to be discharged in a direction of an arrow m by the ejectors 24 a and the discharge rollers 27, after the sorting or the stapling. Subsequently, as shown in FIG. 9, the binding claw 31 passes the ejectors 24 a ahead to receive the bundle of sheets T. Subsequently, the bundle of sheets T is discharged to the stacking tray 21 by the binding claw 31 and the discharge rollers 27. When the binding claw 31 discharges the bundle of sheets T, the ejector clutch 33 is switched and then the ejectors 24 a are returned in a direction of an arrow n by a spring force.

The transverse alignment plate 18 includes a front alignment plate 18 a and a rear alignment plate 18 b. The transverse alignment plate 18 prevents the sheets P from scattering in a transverse direction perpendicular to a supply direction of the sheets P. As shown in FIG. 10, the front alignment plate 18 a is driven by a front alignment motor 36 a and the rear alignment plate 18 b is driven by a rear alignment motor 36 b. The transverse alignment plate 18 includes a front home position sensor 37 a and a rear home position sensor 37 b. The front home position sensor 37 a detects that the front alignment plate 18 a is at a front home position fh of the front alignment plate 18 a. The rear home position sensor 37 b detects that the rear alignment plate 18 b is at a rear home position rh of the rear alignment plate 18 b.

The stapler 20 is disposed on a rear end side in the transport direction of the bundle of sheets T on the platform 17 a. The stapler 20 can staple various positions of sheets. For example, the stapler 20 moves to staple one portion on a front side corner of the sheets, one portion on a rear side corner of the sheets and two portions in the middle of the sheets P according to staple types. As shown in FIGS. 11 and 12, the stapler 20 is supported by a stapler unit 20 a and driven by a stapler shifting motor 40. The stapler shifting motor 40 is a stepping motor, for example. The stapler 20 is driven through a timing belt 41 suspended between a driving pulley 41 a and a driven pulley 41 b by the stapler shifting motor 40. The stapler 20 reciprocates along rails 42. The stapler 20 staples the bundle of sheets T by drive of a stapler motor 43.

Next, a control system will be described focusing on supply and discharge of the sheets P to and from the finisher 7. As shown in FIG. 13, a CPU 210 of a control system 200 of the finisher 7 communicates with the copier 100 through an interface 211. The copier 100 includes a control panel 170 which inputs a setting condition of the finisher 7 or displays the state of the finisher 7. A group of sensors 220 such as the front home position sensor 37 a or the rear home position sensor 37 b is connected to an input terminal of the CPU 210. The buffer tray guide motor 23, the paddle motor 26 a, the longitudinal alignment motor 28, the binding claw motor 32, the ejector clutch 33, the front alignment motor 36 a, the rear alignment motor 36 b, the stapler shifting motor 40, the stapler motor 43, and the like are connected to an output terminal of the CPU 210.

Next, operations of the control system will be described. Various operations of the finisher 7 are input through the control panel 170, for example, when an image formation condition is set in the copier 100.

(1) (In Non-Sorting and Non-Stapling)

When the sheets P supplied from the copier 100 are not subjected to either sorting or stapling, the sheets P discharged from the discharge rollers 161 are distributed in a direction of the first exit rollers 11 by the gate flap 16 to be discharged to the fixing tray 12.

(2) (In Stapling of One Bundle of Sheets)

When just one bundle of the sheets P supplied from the copier 100 is subjected to the stapling, the sheets P are aligned at an intermediate position, and stapled. The intermediate position may be a position of that a center of the sheets P matches up with a center of the processing tray 17. The sheets P discharged from the discharge rollers 161 are distributed in a direction of the second exit rollers 13 by the gate flap 16 to be supplied to the processing mechanism 14. When the preceding sheets P are not present in the processing tray 17, the sheets P are directly supplied from the second exit rollers 13 to the platform 17 a. When the preceding sheets P are being processed in the processing tray 17, the sheets P are supplied from the second exit rollers 13 to the waiting tray 22. After the sheets P are discharged from the processing tray 17, the sheets P on the waiting tray 22 drop to the platform 17 a.

Even when just one bundle of the sheets P supplied from the copier 100 is subjected to the stapling, the sheets P may be supplied to the processing mechanism 14 through the waiting tray 22. Moreover, even when the preceding sheets P are not present in the processing tray 17, the sheets P may be supplied from the second exit rollers 13 to the platform 17 a through the waiting tray 22.

The transverse alignment plate 18 aligns the sheets P supplied to the platform 17 a in a transverse direction of the sheets P. The transverse alignment plate 18 aligns the sheets P to the intermediate position. The front alignment plate 18 a of the transverse alignment plate 18 stays at the front home position fh detected by the front home position sensor 37 a. As indicated by an arrow f of FIG. 10, the rear alignment plate 18 b aligns the sheets P to the intermediate position in such a manner that the rear alignment plate 18 b is reciprocated in a width direction by the rear alignment motor 36 b.

The sheets P are stacked in succession on the platform 17 a and regulated in the rear ends thereof in the transport direction by the rear end stoppers 17 b. The longitudinal alignment rollers 17 c and the discharge rollers 27 rotate in a direction of an arrow q of FIG. 6 and the paddle 26 rotates in a direction of an arrow r. The longitudinal alignment rollers 17 c, the discharge rollers 27, and the paddle 26 longitudinally align the sheets P. During the aligning, the stapler 20 is slid in a direction of an arrow s or a direction of an arrow u of FIG. 12 in accordance with the staple types by the stapler shifting motor 40. The stapler 20 staples the bundle of sheets T on the platform 17 a.

After the stapling, the ejector clutch 33 is connected and the ejectors 24 a are slid in a direction of an arrow m by the binding claw motor 32. The ejectors 24 a are brought into contact with the rear end in the transport direction of the bundle of sheets T to push the bundle of sheets T in the direction of the arrow m. The binding claw 31 passes the ejectors 24 a ahead to push the rear end of the bundle of sheets T and transports the bundle of sheets T to the stacking tray 21. The ejector 24 a is returned in the direction of the arrow n. The discharge rollers 27 rotate in a direction of an arrow o of FIG. 6, transport the bundle of sheets T to the stacking tray 21, and receive the bundle of sheets T in the stacking tray 21.

(3) (In Continuous Stapling Mode)

When the sheets P supplied from the copier 100 are continuously subjected to the stapling, the bundles of sheets T are alternatively shifted in every stapling. The sheets P are shifted before the stapling. A direction of the shifting is perpendicular to the supply direction of the sheets P. An amount of the shifting corresponds to a width of a staple needle, for example.

The sheets P are supplied to the platform 17 a directly or via the waiting tray 22 to be stapled to form the bundle of sheets T as described in (2). However, the transverse alignment plate 18 and the stapler 20 work as follows. As shown in FIG. 14, {circle around (1)} in stapling of a first bundle of sheets, the sheets are shifted from the intermediate position as indicated by two-dot chain line toward the rear side by α (for example, 5 mm) to be transversely aligned. The rear alignment plate 18 b stays at the position where the rear alignment plate 18 b is shifted from the rear home position rh toward the rear side by α. The front alignment plate 18 a is reciprocated in the width direction by the front alignment motor 36 a to shift the sheets P toward the rear side and transversely align the sheets P. The sheets P are regulated by the rear end stoppers 17 b and longitudinally aligned by the longitudinal alignment rollers 17 c, the discharge rollers 27, and the paddle 26. When a predetermined stapling number of sheets P gathers, the stapler 20 staples a first bundle of sheets T1 on the platform 17 a.

For stapling two portions in the middle of the sheets P, for example, the stapler 20 is moved to a location A′ during stacking the first bundle of sheets T1 in the platform 17 a. First, the staple needle A is driven at the location A′. {circle around (2)} Next, the stapler 20 is moved to a location B′ and a staple needle B is driven. After the stapling of the two portions, the ejector clutch 33 is connected and the ejectors 24 a are slid in a direction of an arrow m by the binding claw motor 32. The ejectors 24 a are brought into contact with the rear end in the transport direction of the first bundle of sheets T1 to push the first bundle of sheets T1 in the direction of the arrow m. The binding claw 31 passes the ejectors 24 a ahead to push the rear end of the first bundle of sheets T1 and transports the first bundle of sheets T1 to the stacking tray 21. The ejector 24 a is returned in the direction of the arrow n. {circle around (3)} The discharge rollers 27 rotate in a direction of an arrow o of FIG. 6, transport the first bundle of sheets T1 to the stacking tray 21, and receive the first bundle of sheets T1 in the stacking tray 21.

{circle around (4)} Next, in stapling of a second bundle of sheets, the sheets are shifted from the intermediate position toward the front side by β (for example, 5 mm) to be transversely aligned. The front alignment plate 18 a stays at the position where the front alignment plate 18 a is shifted from the front home position toward the front side by β. The rear alignment plate 18 b is reciprocated in the width direction by the rear alignment motor 36 b to shift the sheets P toward the front side and transversely align the sheets P. The sheets P are regulated by the rear end stoppers 17 b and longitudinally aligned by the longitudinal alignment rollers 17 c, the discharge rollers 27, and the paddle 26.

The stapler shifting motor 40 shifts the stapler 20 toward the front side by the width of the staple needle during the longitudinal alignment of the sheets P. The second bundle of sheets T2 on the platform 17 a is stapled. While the second bundle of sheets T2 are stacked on the platform 17 a, the stapler 20 is moved from the location B′ indicated by a two-dot chain line to a location B″. The staple needle B is driven at the location B″. {circle around (5)} Next, the stapler 20 is moved to a location A″ and the staple needle A is driven. After the stapling of the two portions in the middle of the sheets P, the ejector clutch 33 is connected and the ejectors 24 a are slid in a direction of an arrow m by the binding claw motor 32. The ejectors 24 a are brought into contact with the rear end in the transport direction of the second bundle of sheets T2 to push the second bundle of sheets T2 in the direction of the arrow m. The binding claw 31 passes the ejectors 24 a ahead to push the rear end of the second bundle of sheets T2 and transports the second bundle of sheets T2 to the stacking tray 21. The ejector 24 a is returned in the direction of the arrow n. {circle around (6)} The discharge rollers 27 rotate in a direction of an arrow o of FIG. 6, transport the second bundle of sheets T2 to the stacking tray 21, and receive the second bundle of sheets T2 in the stacking tray 21. The first bundle of sheets T1 and the second bundle of sheets T2 are shifted by (α+β) on the stacking tray 21.

In each stapling of a third bundle of sheets, a fourth bundle of sheets, etc., the rear-side shifting and the front-side shifting are alternatively performed on the platform 17 a to staple the sheets. In the rear-side shift, when the rear alignment plate 18 b is shifted toward the rear side and stays, the rear of the bundle of sheets T is brought into contact with the rear alignment plate 18 b and aligned. In the front-side shift, when the front alignment plate 18 a is shifted toward the front side and stays, the front of the bundle of sheets T is brought into contact with the front alignment plate 18 a and aligned. During performing {circle around (1)} to {circle around (5)} described above, the stapler 20 is moved in an order of A′→B′→B″→A″→A′→B′ . . . to drive the staple needles. When the stapler 20 is moved in an order of A′→B′→B″→A″→A′→B′ . . . during performing {circle around (1)} to {circle around (5)}, a movement distance of the stapler 20 becomes very short.

In the continuous staple mode, the bundles of sheets T on the stacking tray 21 are alternatively shifted toward the front side and the rear side. In this way, it is possible to prevent the staple needles from overlapping at the same location and thus protruding. Moreover, the bundle of sheets T is shifted before the stapling. That is, after the stapling, the bundle of sheets T is able to be discharged from the platform 17 a without delay. Moreover, it is possible to quickly supply the sheets P next subjected to the stapling by the platform 17 a. A shift amount of the bundle of sheets in the continuous stapling mode is not limited. The shift amount may be determined so as to prevent a failure in binding sheets due to protrusion of the staple needle or prevent a failure in receiving the subsequent bundle of sheets, when several bundles of sheets are received in the stacking tray 21.

In the continuous stapling mode, driving timing of a first comparative example in which the bundle of sheets T is shifted after the stapling is compared to driving timing of this embodiment in which the bundle of sheets T is stapled after the shifting. In the stapling, as shown in FIG. 15, the transverse alignment plate 18 shifts the sheets P at t2, while the preceding sheets P wait at t1 in the waiting tray 22 according to this embodiment. After the transverse alignment plate 18 shifts the sheets P, the sheets P are supplied to the platform 17 a. When the previous bundle of sheets reaches a predetermined staple number at t3, the shifting of the bundle of sheets is finished. Between t4 to t5, the stapler 20 is moved to stapling two portions in the middle of the sheets P. The previous bundle of sheets immediately starts to be discharged simultaneously with after the stapling at t5. Subsequent sheets P can wait in advance in the waiting tray 22 at timing of t6.

After the stapling at t5, the discharging proceeds for certain time and then the staple 20 is moved to a subsequent stapling location at t7. The discharging of the previous bundle of sheets is finished at t8. The transverse alignment plate 18 is moved to a subsequent shift location at t9 before the finish of the discharging, since the transverse alignment plate 18 is able to shift the sheets P when the bundle of sheets is not present on the platform 17 a. After the transverse alignment plate 18 shifts the sheets P to a subsequent shifting location, subsequent sheets P are supplied to the platform 17 a. When the bundle of sheets reaches a predetermined staple number at t10, after the shifting of the subsequent bundle of sheets is finished. The stapling starts at t11.

According to the first comparative example, the sheets P is not shifted while the previous bundle of sheets reaches a predetermined staple number in the platform 17 a at c1 and c2 with respect to t1 to t11 of this embodiment. After the previous bundle of sheets reaches the predetermined staple number at c2, the stapling is start at c3. The previous bundle of sheets starts to be shifted simultaneously with the finishing of the stapling at c4. After the stapling at c4, the previous bundle of sheets starts to be discharged simultaneously with after the shifting at c5. Subsequent sheets P can wait in advance in the waiting tray 22 at timing of c6.

The discharging of the previous bundle of sheets is finished at c7. After the bundle of sheets is discharged from the platform 17 a, the subsequent sheets P which are not shifted are supplied to the platform 17 a. When a subsequent bundle of sheets reaches the predetermined staple number at c8, the stapling is start at c9. In the first comparative example, the bundle of sheets at the time of the stapling at c3 is not shifted. Accordingly, during c4 to c9, position movement of the stapler 20 is not required.

According to this embodiment, the sheets P are shifted during t1 to t3 in which the sheets P are supplied to the platform 17 a. According to this embodiment, the bundle of sheets can be discharged simultaneously with the finishing of the stapling. In comparison to this embodiment, according to the first comparative example, the sheets P are not shifted during the sheets P are supplied to the platform 17 a. The shifting starts simultaneously with after the stapling. After the shifting, the bundle of sheets is discharged. In comparison to the first comparative example, the discharging can start earlier, that is, supply timing of the subsequent sheets P to the waiting tray 22 can be advanced by Δt in this embodiment. In comparison to the first comparative example, a processing period of time in the continuous stapling mode can be shortened in this embodiment.

(4) (In Sorting Mode)

When the sheets P supplied from the copier 100 are sorted, first shifting is first performed on the platform 17 a in every sorting. When the bundle of sheets T is discharged to the platform 17 a, second shifting is also performed. A direction of each shifting is perpendicular to the supply direction of the sheets P. The first shifting and the second shifting are performed in the same direction.

The sheets P are supplied to the platform 17 a directly or via the waiting tray 22 to be stapled to form the bundle of sheets T as described in (2). The transverse alignment plate 18 and the stapler 20 work as described in (3) to load the sheets P on the platform 17 a in shifted position. When a first bundle of sheets T3 is shifted toward the rear side to be aligned, as shown in FIG. 16, {circle around (1)} the rear alignment plate 18 b is shifted from the rear home position rh as indicated by two-dot chain line toward the rear side by α (for example, 5 mm). And the rear alignment plate 18 b is stayed. The first bundle of sheets T3 is aligned as the first shifting by the rear of the first bundle of sheets T3 is brought into contact with the rear alignment plate 18 b, which is shifted from the rear home position rh by α and aligned. When the first bundle of sheets T3 reaches a sorting number of sheets, the first bundle of sheets T3 is discharged from the platform 17 a to be received in the staking tray 21.

When the discharging of the bundle of sheets T3 from the platform 17 a, the first bundle of sheets T3 is discharged in the direction of the arrow m oriented toward the stacking tray 21 and simultaneously shifted in a direction of an arrow w oriented toward the rear side perpendicularly to the direction of the arrow m.

The first bundle of sheets T3 is discharged in the direction of the arrow m by the ejectors 24 a as described in (2), the binding claw 31, and the discharge rollers 27. The first bundle of sheets T3 is shifted in the direction of the arrow w by the transverse alignment plate 18. {circle around (2)} During the first bundle of sheets T3 is discharged in the direction of the arrow m, the rear alignment plate 18 b of the transverse alignment plate 18 is further shifted toward the rear side by α′ (for example, 5 mm) as the second shifting from the location where is shifted from the rear home position rh toward the rear side by α (for example, 5 mm). The rear alignment plate 18 b is shifted toward the rear side by α+α′=10 mm from the rear home position rh. The front alignment plate 18 a is reciprocated by the front alignment motor 36 a in the width direction to transversely align the sheets, during the shifting of the first bundle of sheets T3 in the direction of the arrow w. {circle around (3)} The first bundle of sheets T3 is slid on the platform 17 a in a direction of an arrow x of FIG. 16 to be received in the stacking tray 21.

A second bundle of sheets T4 is shifted toward the front side to be aligned and sorted. As shown in FIG. 16, {circle around (4)} the front alignment plate 18 a is shifted from the front home position fh indicated by a two-dot chain line by β (for example, 5 mm), and stays. The second bundle of sheets T4 is aligned as the first shifting by the front of the second bundle of sheets T4 is brought into contact with the front alignment plate 18 a, which is shifted from the front home position fh by β, and aligned. When the second bundle of sheets T4 reaches a sorting number of sheets, the second bundle of sheets T4 is discharged from the platform 17 a.

When discharging the second bundle of sheets T4 from the platform 17 a, the second bundle of sheets T4 is discharged in the direction of the arrow m oriented toward the stacking tray 21 and simultaneously shifted in a direction of an arrow y oriented toward the front side perpendicularly to the direction of the arrow m. {circle around (5)} During the second bundle of sheets T4 is discharged in the direction of the arrow m, the front alignment plate 18 a of the transverse alignment plate 18 is further shifted toward the front side by β′ (for example, 5 mm) as the second shifting from the location where is shifted from the front home position fh toward front side fh by β. The front alignment plate 18 a is shifted toward the front side by β+β′=10 mm from the front home position fh. The rear alignment plate 18 b is reciprocated by the rear alignment motor 36 b in the width direction to transversely align the sheets during the shifting of the second bundle of sheets T4 in a direction of an arrow y. {circle around (6)} The second bundle of sheets T4 is received in the stacking tray 21, during sliding on the platform 17 a in a direction of an arrow z of FIG. 16.

In each sorting of a third bundle of sheets, a fourth bundle of sheets, etc., the two step rear-side shifting and the two step front-side shifting are alternatively performed to sort the bundle of sheets T. In the two step rear-side shifting, in a first step, when the rear alignment plate 18 b is shifted by α toward the rear side and stays, the bundle of sheets T is brought into contact with the rear alignment plate 18 b and subjected to the first shifting. In a second step, when the rear alignment plate 18 b is further shifted by α′ toward the rear side and stays, the bundle of sheets T is brought into contact with the rear alignment plate 18 b and subjected to the second shifting to be aligned,. In the two step front-side shifting, in a first step, when the front alignment plate 18 a is shifted by β toward the front side and stays, the bundle of sheets T is brought into contact with the front alignment plate 18 a and subjected to the first shifting. In a second step, when the front alignment plate 18 a is further shifted by β′ toward the front side and stays, the bundle of sheets T is brought into contact with the front alignment plate 18 a and subjected to the second shifting to be aligned. The bundle of sheets T is shifted by (α+α′+β+β′=20 mm) on the stacking tray 21. Moreover, in the sorting mode, the shift amounts of plural bundles of sheets T are not limited to the amount described above, but a shift amount may be determined as long as a bundle of sheets is apparently sorted.

In the sorting, during the discharging of the bundle of sheets T, the bundle of sheets T may be shifted in the direction of the arrow w or the direction of the arrow y perpendicular to the direction of the arrow m simultaneously with the discharging in the direction of the arrow m. A friction force applied to the bundle of sheets T is distributed in the direction of the arrow m and the direction of the arrow w or in the direction of the arrow m and the direction of the arrow y. In this embodiment, the friction force in the direction of the arrow m which is applied to a front end of the bundle of sheets T in the direction of the arrow m can be reduced, compared to a case where the bundle of sheets T is discharged only in the direction of the arrow m in the discharging from the platform 17 a. As indicated by a full line in FIG. 17, the bundle of sheets T is received in the stacking tray 21 without bending in the discharging from the platform 17 a. For example, when the friction force in the direction of the arrow m is focused on the front end of the bundle of sheets T, some brakes are applied over the front end of the bundle of sheets T. The bundle of sheets T is bent because of the friction force as indicated by a dotted line of FIG. 17. Thereby the aligning of the bundle of sheets T is disturbed.

In the sorting mode, the bundle of sheets T may be selectively discharged from the platform 17 a. For example, as for the bundle of sheets T which is easy to be bent, the bundle of sheets T is shifted in the direction of the arrow w or in the direction of the arrow y during the discharging of the bundle of sheets T in the direction of the arrow m in the discharging. As for the bundle of sheets T which is difficult to be bent, after the bundle of sheets T is shifted by the whole shift amount on the platform 17 a, the bundle of sheets T may be discharged in the direction of the arrow m without the shifting in the width direction in the discharging. The bundle of sheets easy to be bent in the discharging may be a bundle of sheets T having a long size in the discharge direction or a bundle of sheets T formed by thin sheets P having weak resilience. The type of the sorting mode is selected through the control panel 170.

The operations for the bundle of sheets in the sorting mode are not limited to the operations described above. The shifting may not be divided into the two steps, that is, the first shifting and the second shifting, when the bundle of sheets T is shifted toward the rear side or the front side. However, the bundle of sheets T is just shifted while the bundle of sheets T is discharged from the platform 17 a. For example, the bundle of sheets T is aligned on the platform 17 a of the intermediate position. When the discharging of the bundle of sheets T from the platform 17 a, the plural bundles of sheets T may be moved alternatively in the direction of the arrow x or in the direction of the arrow z shown in FIG. 16 and then sorted.

In the continuous stapling mode, when the number of the bundles of sheets T to be stapled is small, the bundle of sheets T may be just shifted during the discharging of the bundle of sheets T from the platform 17 a. For example, the bundle of sheets T is shifted on the shift support surface 17 a to be stapled of the intermediate position. The bundles of sheets T which is stapled are discharged from the platform 17 a and received in the stacking tray 21, during alternative movement in the direction of the arrow x or the direction of the arrow z as shown in FIG. 16. The staple needles of sheets T are alternatively shifted, and then the bundles of sheets T are received in the stacking tray 21. In this case, the number of the bundles of sheets T is limited to a small number of the bundles of sheets T which do not give a large load to the transverse alignment plate 18 in the shifting after the stapling.

According to the first embodiment, the bundle of sheets T is shifted to be stapled in the continuous stapling mode. The bundle of sheets T is discharged simultaneously with the finishing of the stapling. Accordingly, it is not necessary to shift the bundle of sheets T after the finishing of the stapling. After the finishing of the stapling, supply timing of the subsequent sheets P can be accelerate. Processing time in the continuous stapling mode can be shortened. According to the comparative example in which the bundle of sheets T is shifted after the stapling, it is necessary to increase the driving torque of the transverse alignment plate 18 shifting the bundle of sheets T, when the number of the bundles of sheets T is much. However, according to this embodiment, the sheets P supplied from the copier 100 are shifted in succession to be stacked on the platform 17 a. According to this embodiment, it is possible to shift the sheets P with small driving torque. The front alignment motor 36 a of the front alignment plate 18 a and the rear alignment motor 36 b of the rear alignment plate 18 b can be miniaturized and manufactured with low cost.

According to the first embodiment, when the bundle of sheets T is discharged from the platform 17 a in the sorting mode, the bundle of sheets T is discharged during the shifting of the bundle of sheets T in the direction which is perpendicular to the discharge direction. The friction force applied to the front end of the bundle of sheets T in the discharging can be distributed in the discharge direction and the direction which is perpendicular to the discharge direction. The friction force applied to the front end of the bundle of sheets T in the discharge direction can be reduced. Even when the size of the sheets P in the discharge direction is large or rigidity of the sheets P is weak, it is possible to prevent the bundle of sheets T from being bent since the front end of the bundle of sheets T is applied some brakes. According to the first embodiment, it is possible to prevent the sheets from skewing due to abrupt shifting, since a distance shifted one time can be reduced by shifting the sheets several times, as in the first shifting on the platform 17 a and the second shifting in the discharging in the sorting mode.

Next, a second embodiment will be described. According to the second embodiment, an alignment location of the bundle of sheets is adjusted in accordance with the size of the sheets in the stapling in the first embodiment described above. Other details can be the same as explained in the first embodiment. In the second embodiment, the same reference numerals are given to the same constituent elements as described in the first embodiment, and the detailed description is omitted.

The stapler 20 of the finisher 7 staples one portion on a front side corner of the sheets, one portion on a rear side corner of the sheets, or two portions in the middle of the sheets P. The stapler 20 rotates to staple the sheets upon stapling one portion on the front side corner or one portion on the rear side corner, as shown in FIG. 11. The stapler unit 20 a needs a space for the rotational motion of the stapler 20 and a space for maintenance. In the maintenance, for example, a staple needle may be supplemented. According to the second embodiment, as shown in FIG. 18, a home position (HP) of the stapler 20 is on the front side. The home position (HP) has a space for maintenance.

The transverse alignment plate 18 of the finisher 7 needs a reciprocation width for alignment. For example, in FIG. 10, when the front alignment plate 18 a is stayed, the rear alignment plate 18 b reciprocates, as indicated by an arrow f, transversely to align the sheets P. The finisher 7 needs to ensure a space for the stapling and the transverse alignment, and the size and weight of the finisher 7 needs to be reduced. The second embodiment satisfies these requirements.

According to the second embodiment, the alignment location of the bundle of sheets T is adjusted in accordance with the size (sheet width) of the sheets P in a direction perpendicular to the supply direction, and driving the stapler 20 is controlled in accordance with the adjustment of the alignment location. When the sheet width is smaller than a predetermined size, a center reference θ of the platform 17 a, which is indicated by chain line of FIG. 18, serves as the center of the location where the bundle of sheets T is aligned. When the transversely aligning of the bundle of sheets T, as shown in FIG. 18, the front alignment plate 18 a stays at a first position (f1). When the front of the bundle of sheets T is brought into contact with the first position (f1) and the bundle of sheets T is transversely aligned, the center of the bundle of sheets T matches with the center reference θ. The bundle of sheets T is transversely aligned on the basis of a center reference in which the center of the bundle of sheets T matches with the center reference θ by reciprocating the rear alignment plate 18 b in a width direction indicated by an arrow g. The front home position is detected by the front home position sensor 37 a shown in FIG. 10.

When the sheet width is equal to or larger than the predetermined size, a front reference k indicated by chain line of FIG. 19 serves as the center of the alignment location of the bundle of sheets T. The front reference k is a location where the bundle of sheets is shifted by a shift amount λ from the center reference θ of the platform 17 a toward the front side. When transversely aligning the bundle of sheets T, as shown in FIG. 19, the front alignment plate 18 a is shifted from a second position (f2) indicated by a chain line by the shift amount λ toward the front side. The second position (f2) is a position where the front alignment plate 18 a stays upon transversely aligning the bundle of sheets T on the basis of the center reference in which the center of the bundle of sheets T matches with the center reference θ. The bundle of sheets T is transversely aligned by staying the front alignment plate 18 a at the location where-is shifted by the shift amount λ from the second position (f2). When the front of the bundle of sheets T is brought into contact with the front alignment plate 18 a to transversely align the bundle of sheets T, the center of the bundle of sheets T matches with the location of the front reference k. The bundle of sheets T is transversely aligned on the basis of a front reference in which the center of the bundle of sheets T matches with the front reference k, by reciprocating the rear alignment plate 18 b in the width direction indicated by the arrow g.

The sheet width of the predetermined size refers to a width obtained by reducing (the shift amount λ of the transverse alignment plate 18) from (the maximum sheet width capable of the stapling). That is, when (a sheet width L)<{(the maximum sheet width capable of the stapling)−(the shift amount λ of the transverse alignment plate)}, the bundle of sheets T is aligned on the basis of the center reference.

When (the sheet width L)≧{(the maximum sheet width capable of the stapling)−(the shift amount λ of the transverse alignment plate)}, the bundle of sheets T is aligned on the basis of the front reference.

In order to ensure a reciprocation space of the rear alignment plate 18 b for the transverse alignment, the alignment location of the bundle of sheets T is adjusted. The maximum rear-side movement limit of the stapler 20 for stapling one portion on the rear side corner may be moved by the shift amount λ of the transverse alignment plate toward the front side.

For example, on the assumption that the maximum sheet width capable of the stapling is the length (297 mm) of the JIS standard A4 transversal size, the shift amount λ of the transverse alignment plate 18 is set to 20 mm. In this case, the sheets P having the sheet length of 277 mm or more may have an A4 transversal size or A3 size of the JIS standard or the letter or ledger size of a US standard. When the bundle of sheets T having the above size is stapled in the one portion on the rear side corner, the bundle of sheets T is aligned on the basis of the front reference. In addition, the bundle of sheets T having a size less than 277 mm is aligned on the basis of the center reference.

For example, when the bundle of sheets T having the sheet length of a predetermined size (for example, 277 mm) or more is aligned on the basis of the center reference to staple the bundle of sheets T in the one portion on the rear side corner, the stapler 20 needs a space on the rear side and thus has to move up to a location indicated by a chain line SP of FIG. 19. When the bundle of sheets T having the sheet length of the predetermined size (for example, 277 mm) or more is aligned on the basis of the front reference, the maximum movement location of the stapler 20 is reduced up to a location indicated by a full line RP of FIG. 19. The maximum movement location RP of the stapler 20 on the rear side becomes closer by the shift amount λ (20 mm) from the dotted-line SP toward the front side. As for the bundle of sheets T having the sheet length less than the predetermined size (277 mm), the reciprocation space of the rear alignment plate 18 b can be sufficiently ensured, even when the bundle of sheets T is aligned on the basis of the center reference. Moreover, the stapler 20 can move up to the location indicated by the full line RP on the front side.

When the alignment location of the bundle of sheets is adjusted, the maximum sheet width capable of the stapling or the shift amount of the transverse alignment plate is not limited. When the home position (HP) of the stapler is provided on the rear side, the alignment location of the bundle of sheets which having the sheet width of a predetermined size or more may be shifted on the rear side.

According to the second embodiment, when the stapling of one portion on a rear side corner of the sheets by the stapler 20, the alignment location of the bundle of sheets T having the sheet width of the predetermined size or more is shifted on the front side. Even in the bundle of sheets T having the sheet width of the predetermined size or more, a reciprocation width g of the rear alignment plate 18 b can be sufficiently ensured. The maximum movement location of the stapler 20 on the rear side can be shifted on the front side. The size of the finisher 7 in the sheet width direction can be reduced. It is possible to design the lightweight finisher 7. Moreover, when the movement distance of the stapler 20 stapling the bundle of sheets is shortened, a noise occurring due to the movement can be reduced and movement time can be shortened.

The invention is not limited to the above-described embodiments, but may be modified into various forms within the scope of the invention. For example, the image forming apparatus includes apparatuses such as a color copier. The shape of the processing tray or the structure of the sheet transporting member is not limited. Functions of the processing member are not limited to the sorting function and the stapling function. A function of punching sheets or a function of folding sheets may be arbitrarily included. 

1. A sheet finishing apparatus comprising: a processing tray which stacks a plurality of sheets; a processing member which finishes the sheets; a receiving member which receives the plurality of sheets discharged from the processing tray in a discharge direction; and a sheet transporting member which transports the plurality of sheets from the processing tray to the receiving member while shifting the plurality of sheets in a direction perpendicular to the discharge direction.
 2. The apparatus according to claim 1, wherein the sheet transporting member transports a first plurality of sheets from the processing tray to the receiving member while shifting the first plurality of sheets in a first direction, and transports a second plurality of sheets from the processing tray to the receiving member while shifting the second plurality of sheets in a second direction opposite to the first direction.
 3. The apparatus according to claim 2, wherein the first direction and the second direction are perpendicular to the discharge direction.
 4. The apparatus according to claim 1, wherein the processing member includes a shifter which shifts the sheets supplied to the processing tray in the direction perpendicular to the discharge direction.
 5. The apparatus according to claim 4, wherein the shifter includes a transverse alignment member which aligns ends of the plurality of sheets stacked on the processing tray in the direction perpendicular to the discharge direction.
 6. The apparatus according to claim 1, wherein the processing member includes a stapler which staples the plurality of sheets stacked on the processing tray.
 7. The apparatus according to claim 1, wherein the sheet transporting member shifts the sheets having a size longer in the discharge direction than a predetermined size, and does not shift the sheets having a size shorter in the discharge direction than the predetermined size.
 8. The apparatus according to claim 1, wherein the sheet transporting member shifts the sheets having weight lighter than a predetermined basis weight in the direction perpendicular to the discharge direction and does not shift the sheets having a weight heavier than the predetermined basis weight in the direction perpendicular to the discharge direction.
 9. The apparatus according to claim 1, wherein the sheet transporting member includes a travel member and a transverse alignment member.
 10. An image forming apparatus comprising: an image forming member which forms an image on a sheet; a processing tray which stacks a plurality of the sheets supplied from the image forming member; a processing member which finishes the sheets; a receiving member which receives the plurality of sheets discharged from the processing tray; and a sheet transporting member which transports the plurality of sheets from the processing tray to the receiving member while shifting the plurality of sheets in a direction perpendicular to the discharge direction.
 11. The apparatus according to claim 10, wherein the sheet transporting member transports a first plurality of sheets from the processing tray to the receiving member while shifting the first plurality of sheets in a first direction, and transports a second plurality of sheets from the processing tray to the receiving member while shifting the second plurality of sheets in a second direction opposite to the first direction.
 12. The apparatus according to claim 11, wherein the first direction and the second direction are perpendicular to the discharge direction.
 13. The apparatus according to claim 10, wherein the processing member includes a shifter which shifts the sheets supplied to the processing tray in the direction perpendicular to the discharge direction.
 14. The apparatus according to claim 13, wherein the shifter includes a transverse alignment member which aligns ends of the plurality of sheets stacked on the processing tray in the direction perpendicular to the discharge direction.
 15. The apparatus according to claim 10, wherein the processing member includes a stapler which staples the plurality of sheets stacked on the processing tray.
 16. The apparatus according to claim 10, wherein the sheet transporting member shifts the sheets, which has a size longer in the discharge direction than a predetermined size, in the direction perpendicular to the discharge direction.
 17. The apparatus according to claim 10, wherein the sheet transporting member shifts the sheets having a size longer in the discharge direction than a predetermined size, and does not shift the sheets having a size shorter in the discharge direction than the predetermined size.
 18. The apparatus according to claim 10, wherein the sheet transporting member includes a travel member and a transverse alignment member.
 19. A sheet finishing method comprising: stacking sheets in a processing tray; discharging the plurality of sheets stacked in the processing tray from the processing tray, while shifting the sheets in a direction perpendicular to a discharge direction of the sheets; and stacking the plurality of sheets discharged from the processing tray.
 20. The method according to claim 19, further comprising: shifting the sheets supplied to the processing tray in the same direction as a shift direction in the discharging. 